Maximum extended advertising data length supported

RE: Maximum extended advertising data length supported

manumonti — Wed, 18 Dec 2019 15:31:56 GMT

Hi Kenneth.

So, are there any way for chaining "manually" more packets?

I'm interested on advertise more than 255 bytes.

Manuel Montenegro

RE: Maximum extended advertising data length supported

Olivier Balitch — Fri, 21 Sep 2018 06:55:58 GMT

Hi Kenneth,

Ok, that's very clear.

Thanks.

Best regards,

Olivier

RE: Maximum extended advertising data length supported

Kenneth — Thu, 20 Sep 2018 17:44:10 GMT

Hi,

BLE_GAP_ADV_SET_DATA_SIZE_EXTENDED_MAX_SUPPORTED is the total number of bytes supported, in this case 255 bytes, this means that the total number of "chained" advertisement packets are up to 2 (or 1 depending on whether you call the first packet "chained"). Two packets are required since 255 bytes will not fit into one advertisement packet due to headers. I agree it is slightly odd calling it "chained" advertisement packets, since the second packet is only a few bytes long in most cases.

Best regards,
Kenneth

RE: Maximum extended advertising data length supported

Olivier Balitch — Thu, 20 Sep 2018 15:42:06 GMT

Hi Kenneth,

Thanks for your quick feedback. If I understand you correctly, you are saying that chained advertisement is supported and that the on air packet can contain up to 255 bytes.

The BLE_GAP_ADV_SET_DATA_SIZE_EXTENDED_MAX_SUPPORTED is the define being used to limit the number of bytes per packet. Is that correct?

What is the maximum number of chained packet supported or the maximum supported length for extended advertising data with s132 softdevice & nRF52832?

How do you ensure user does not provide more than 1650 bytes (length given in the BLE Core specification)?

Best regards,

Olivier

RE: Maximum extended advertising data length supported

Kenneth — Thu, 20 Sep 2018 11:34:37 GMT

Hi,

The hardware limit the maximum on-air packet to 255 bytes, in this case the 255 bytes must be split between adv mode, extended headers and advertisement data. The softdevice api have limited the max advertisement data also to 255 bytes (likely due to some internal implementation trade-offs).

Then depending on the length of the total advertisement packet (mode+headers+data), it may be split into 2 on-air packets, hence the advertisement packets are chained.

Best regards,
Kenneth